Peripheral arterial disease (PAD) represents one of the major vascular diseases induced by age. The gold- standard treatment for severe PAD is surgery or endovascular revascularization. However, a third of patients are not suitable for surgery and most of them will die due to complications. Therapeutic angiogenesis strategies that are based on cell therapy or the delivery of angiogenic growth factors have shown great potential for the treatment of critical limb ischemia in a number of animal and clinical studies. Stem cell therapy associated with three-dimensional, biologically inspired constructs represents a promising therapy for vascular regeneration. Marrow-isolated adult multilineage inducible (MIAMI) cells, a highly homogeneous sub- population of mesenchymal stromal cells (MSCs), have been extensively characterized in our lab for the past 15 years. MIAMI cells derived have the capacity to respond to trophic factors and develop phenotypic and functional characteristic of mature vascular endothelial cells in vitro and in vivo. The objective of this proposal is to develop three-dimensional cellular constructs with distinct architectural and biological cues and determine their angiogenic potential in an in vitro and in vivo setting. We hypothesize that guided therapeutic angiogenesis could be attained by controlling the spatial presentation of MIAMI cells seeded on bioinspired polymeric constructs that are implanted in regions of ischemia. We conjecture that the transplanted MIAMI cellular sheets will be successfully engrafted into the ischemic tissue stimulate revascularization and mature vessel formation. We will test our hypothesis by pursuing two specific aims. In AIM I we will design nanofibrous three-dimensional cellular sheets with defined architectural and biological signals. We will use a state-of-the- art fabrication process to prepare electrospun gelatin constructs and will functionalize th surface of the construct's nanofibers with biological epitopes that promote MIAMI cell adhesion. The angiogenic activity of the MIAMI cellular sheets will be assessed as a function of fabrication parameters in a 3-D in vitro angiogenesis assay. In AIM II will determine the capacity of the MIAMI cellular constructs to promote vessel formation, maturation and direction in vivo. Furthermore, we will determine the effect of aging on the ability of MIAMI cells, seeded on three dimensional constructs, to promote vascular repair in an aged mouse model of critical limb ischemia.